The original price is $70.00
The problem states that $59.50 is the discounted price, this means that it is not the 100% price of the aquarium. Since 15% is the discount, the remaining price is equivalent to 85% of the original price, which amount to $59.50.
100% - 15% = 85%
100% - 15% = $59.50
To get original price, we must divide the discounted price by its corresponding percentage.
$59.50 / 85% = original price
$59.50 / 0.85 = $70
To check, we must get the 15% equivalent amount from the original price.
$70 x 15% = $10.50 discount value
$70 - $10.50 = $59.50 discounted price